Python: scope executor activity IDs to workflow runs

[Naveen Chatlapalli (1aifanatic)]

Motivation & Context

Executor activity snapshots currently reuse IDs such as executor:researcher across workflow runs. A UI or message store keyed by message ID can overwrite the activity from an earlier turn.

Description & Review Guide

• What are the major changes? Prefix the executor activity message ID with the length-prefixed AG-UI run ID so unrestricted component strings cannot collide. Add regression cases for completion and failure paths across two runs and two executors, plus the delimiter-collision case.
• What is the impact of these changes? Progress and terminal snapshots for an executor still update the same activity within a run, while distinct runs have distinct activity IDs. The executor identity remains available in content.executor_id; no public API or dependency is added.
• What do you want reviewers to focus on? Within-run update identity and separation across runs. The original two cases fail before run scoping; the delimiter case fails before length-prefixing. The complete AG-UI package suite passes: 1,370 passed, 14 skipped (12 existing deprecation/AsyncMock warnings). Changed-file Ruff lint/format and package-configured Pyright pass. Cross-package tests were not run.

Related Issue

Fixes #7338. Checked the issue discussion, cross-references, and open PRs; no competing implementation was found. The related #7429 concerns lifecycle/thread correlation and explicitly excludes activity message IDs.

Contribution Checklist

• The code builds clean without any errors or warnings
• All unit tests pass, and I have added new tests where possible
• The PR follows the Contribution Guidelines
• This PR is linked to an issue and there is no other open PR for this issue (see Related Issue above).
• This is not a breaking change.

[Copilot]

Copilot review overview

🟡 Changes recommended

The delimiter-based ID format permits collisions between unrestricted run and executor IDs.

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Review effort: Balanced
Findings: 1

Open (1)

• Use collision-safe encoding for composite run and executor IDs · New

What changed in this PR

Scopes executor activity IDs to workflow runs to prevent cross-run snapshot overwrites.

Changes:

• Prefixes activity IDs with the run ID.
• Adds completion and failure regression coverage across runs and executors.

File	Description
python/​packages/​ag-ui/​agent_framework_ag_ui/​_workflow_run.py	Adds run-scoped executor activity IDs.
python/​packages/​ag-ui/​tests/​ag_ui/​test_workflow_run.py	Tests activity identity and run separation.

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